1. Field of the Invention
The present invention relates to a communication method and a communication apparatus useful in the case where radio frequency interference occurs and to a program that causes a computer to perform the communication method.
2. Description of the Related Art
In recent years, a wireless local area network (LAN) system standardized as Institute of Electrical and Electronics Engineers (IEEE) 802.11 has a higher speed due to the introduction of IEEE 802.11b, IEEE 802.11g, and IEEE 802.11n, which exceeds 100 Mbps.
Furthermore, in order to cope with stream data transmission, IEEE 802.11e, which supports a Quality of Service (QoS) technique, has also been standardized.
The increase in speed and the relatively inexpensive cost to establish wireless LANs, the number of wireless LAN apparatuses installed and used in homes has increased. As a result of the increase in number of installed apparatuses has increased, so has the problem of potential radio frequency interference occurring between the apparatuses.
In the IEEE 802.11b and IEEE 802.11g wireless LAN systems, a wireless radio frequency band of the Industrial Scientific and Medical (ISM) band is used, which can also be used by a wireless apparatus other than a wireless LAN apparatus, i.e., wireless non-LAN apparatus. Accordingly, a radio frequency band used by a wireless non-LAN apparatus may overlap with a radio frequency band used by a wireless LAN apparatus, thus causing radio frequency interference.
In order to solve radio frequency interference occurring between wireless LAN apparatuses and between a wireless LAN apparatus and a wireless non-LAN apparatus, various methods have been proposed (see, for example, Japanese Patent Application Laid-Open No. 2002-158667 and Japanese Patent Application Laid-Open No. 2004-336387).
Radio frequency interference becomes especially problematic when performing a band-control type communication used in a stream data transmission. For example, in the case of a centralized control method in which an access control is performed based on polling from an access point to secure a band, if radio frequency interference occurs during sending and receiving of data, data communication may be delayed, and accordingly, a desired data communication rate may not be secured. As a result, a buffer underrun may occur in a receiving apparatus or a buffer overrun may occur in a sending apparatus.
U.S. Patent Application Publication No. US 2003/0125087 A1 (Japanese Patent Application Laid-Open No. 2003-198564), Japanese Patent Application Laid-Open No. 2000-253017, and Japanese Patent Application Laid-Open No. 08-274788 discuss methods for switching between a centralized control method and a distributed control method.